Historically, cyclists have had to choose between lightweight, well-vented helmets, and aerodynamic helmets that are bigger, heavier, and legal only for time trials and triathlons. With the all-purpose Air Attack, Giro aims to achieve superior aerodynamics without sacrificing weight or venting.

The unusual-looking lid is different from any other modern road helmet we’ve seen. Minimal venting and a rounded shape give it styling reminiscent of urban helmets. The company says the aerodynamic performance is similar to its Selector time trial helmet, but has far better ventilation. The result, Giro adds, is a helmet that’s both practical and legal for all races.

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“The Air Attack essentially creates an entirely new category of helmets that are light, cool, and aerodynamically efficient at the same time,” said Giro Senior Brand Manager Eric Richter in a statement.

Giro worked with aerodynamicist Len Brownlie to design a similar frontal profile to the Selector. But, in place of the teardrop tail, the Air Attack has a blunter trailing edge. As air flows around an object, at some point the airflow separates from the object and becomes turbulent, increasing drag. The goal of aerodynamic design is always to reduce this separation, resulting in cleaner airflow and less drag. By controlling the frontal area and curvature on this helmet, Giro is able to tailor the separation point to make the air behave as if it’s flowing over a longer tail. But, without the tail itself, the helmet has better aerodynamics in crosswinds, and when a rider turns his or her head.

Directing airflow in such a precise manner requires minimizing the vents, and results in a hotter head. To overcome that problem, Giro designed a new fit system called Roc Loc Air. The system suspends the helmet shell about three millimeters off the wearer’s head. When high-pressure air hits the rider’s helmeted forehead, the velocity increases as it travels through the helmet, cooling the rider’s head without drag-inducing vents. A Giro representative told us that in terms of aerodynamics and cooling, the Air Attack’s performance is between the Selector time trial model and the Aeon road model.